Water-level control



Jan. 17, 1950 s. w. E. ANDERSSON WATER LEVEL CONTROL Filed Aug. 24, 1944 INVENTOR Patented Jan. 17, 1950 WATER-LEVEL CONTROL Sven W. E. Andersson, Evansville, Ind., assignor to Servel, Inc., New York, N. Y., a corporation of Delaware Application August 24, 1944, Serial No. 551,032

Claims.

My invention relates to water level controls and more particularly to a water level control for atmospheric steam boilers wherein no mechanical movement has to be transmitted through the boiler wall thereby eliminating the need of the usual flexible seal and mechanical movements. My improved water level control is based upon a thermal, rather than a mechanical, principle.

It is, therefore, an object of my invention to provide a water level control for atmospheric steam boilers based upon a thermal principle and wherein the parts of said control which are in open communication with the water and/or steam spaces of said boiler are stationary.

t is a further object of my invention to provide a water level control wherein the supply of heat to an atmospheric boiler is cut off in the event that feed water is not supplied to said boiler within a predetermined time after a feed water supply valve has been opened.

These and other objects and advantages of my invention will become more apparent when considered in connection with the following description and accompanying drawing which forms a part of this specification, and wherein:

Fig. 1 is a side view, partly in section, of a steam boiler incorporating my improved control; and

Fig. 2 is a vertical sectional view taken on line 22 of Fig. 1.

Referring now to the drawing, wherein like reference characters are used to designate like parts, It designates generally an atmospheric steam boiler provided with a gas burner H, a gas combustion and heating tube l2, a plurality of heating tubes IS, a combustion chamber M, at one end of the combustion and heating tubes, and a flue l5 at the opposite end of the heating tubes. The gas burner I is provided with a fuel gas supply conduit 6, a pilot tube l1 and a valve control l8 to be described presently. Combustible gas supplied to the burner H is adapted to project a flame into the combustion and heating tube |2 and the hot products of combustion pass 1 into the chamber I4, through the heating tubes [9 and out the flue l5, as indicated by the arrows in Fig. 1. A feed water supply conduit l9, connected to any suitable source of water as a city main, supplies feed water through a valve control 20 and an inlet conduit 2| into the boiler. A conduit 22 connected to inlet conduit 2| returns condensate to the boiler. A steam or vapor outlet 23 leads from the top portion of the boiler.

Th above-described structure, which is generally known to be old in the art, is one form of atmospheric steam boiler with which my improved water level control is adapted to be incorporated.

My improved water level control comprises a compartment 25 permanently attached to one side of the boiler, as by welding or the like, and is in open communication with the water and steam spaces of the boiler by openings 26 and 21 respectively. Compartment 25 is otherwise closed. A tubular casing or bulb well 28 is provided within the upper portion of compartment 25, and is adapted to receive a thermal bulb 29 which is connected by a capillary tube 39 to an expansible and contractible bellows 3|. The bulb 29, capillary tube 39 and bellows 3| constitute a thermostat and contain a suitable fluid which changes in volume with a change in temperature. The bulb well 28 and thermal bulb 29 are normally submerged in water in the compartment 25, the level of which is always substantially the same as the water level in the boiler I0. A heat transfer rod 32, made of steel or other suitable heat transfer metal, is connected to the bulb well i 28, and, as shown in Fig. 2, extends vertically upward from said well, then horizontally and then downward and into the upper portion of combustion chamber M to transfer heat from the hot products of combustion in said chamber to the thermostatic bulb 29 located in said well. A tubular casing 33 surrounds the rod 32 to prevent the boiling water in the water space and the steam or vapor in the steam space of the boiler from cooling this rod. The arrangement is such that the temperature of heat transfer rod 32 is not influenced by the water or the steam in the boiler proper and that so long as the bulb well 28 is in contact with the water in compartment 25, said water will consume the heat transferred by said rod and little or no heat will be transferred to the thermostatic bulb 29 by the heat transfer rod.

The bellows 3| is fixed at one end to a support 35 and the expansion and contraction of said bellows, due to the expansion and contraction of the fluid in thermal bulb 29, is utilized to control a switch 36 in an electric circuit in which is connected the feed water supply valve control 20. The switch 36 is of the snap-acting type and includes upper and lower toggle arms 31 and 38 pivotally connected at their inner ends to a suitable support 39. A coil spring 40 is connected between the outer ends of toggle arms 31 and 38. The outer end of toggle arm 38 is connected by a link 4| tothe movable end of bellows 3|. The

outer end of toggl arm 31 is provided with a contact 42 which is adapted to engage a fixed contact 43 connected to a conductor 44 which leads to a solenoid coil 45 of control device 20. The inner end of toggle arm 31 is connected by a conductor 49 to a main conductor 41, the inner end of toggle arm 31 being insulated in any suitable manner from the pivotal support 39 and from other elements that make up the toggle. The circuit is completed through the solenoid coil 45 by means of a conductor 48 which is connected to a main conductor 49. Main conductors 41 and 49 are connected to a suitable source of electricity. The solenoid coil 45 of control 20 is formed to receive a plunger 50 to which is fixed a valve When solenoid coil 45 is energized, the plunger 50 is raised and valve 5| is opened to permit flow of feed water into the boiler. When solenoid coil 45 is deenergized, which is its normal condition, the plunger 50 moves downward by gravity to close the feed water valve 5| A coil spring 52 tends to urge theplunger 50 and attached valve 5| downward.

The control 58 in the gas supply conduit is quite similar to control 29 in the feed water supply conduit, except the solenoid coil is normally energized so that the valve in the gas supply conduit is normally open. Control l8 comprises a solenoid coil 53 formed to receive a plunger 54 to which is attached a valve 55 which controls the supply of gas to burner ii. Plunger 54 and attached valve 55 are urged downward by a coil spring 55. Control is is in reality a safety cutoff. In practice, a modulating valve controlled responsive to the demands on the boiler would be included in the burner control. Solenoid coil 53 is connected directly to main conductors 41 and 49 and as stated above, this coil is normally energized. A switch 51 in conductor 41 opens the entire electric circuit. Switch 51 is of the snapacting type and includes toggle arms 58 and 59 biased toward off-center positions by means of a coil spring 55. The inner ends of toggle arms 58 and 59 are pivoted upon a support 6|. The outer end of toggle arm 58 is provided with a link 62 to which is connected a bridge 63 adapted to close the circuit between contacts 64 and '65 in conductor 41. The outer end of toggle arm 59 is connected to the armature 66 of a relay 61 by means of a link 58, a lever 69 and a second link 15. Lever 69, which is pivoted on a suitable support, is connected by a link 1| to the piston rod 12 of a dash pot 19. The arrangement is such that when the relay is energized, togglearm 59 is moved in a clock-wise direction from its position shown in Fig. 1, but due to the resistance offered by dash pct 13 and the snap action of toggle arms 53 and 59, there is a delay or lapse of time between the time when the relayis energized and the time when bridge 53 carried by toggle arm 58 opens the circuit in main conductor 4?. Relay 81 is connected by conductors 14 and 15 to conductors 44 and 49 respectively, so that the circuit to the relay is'closed whenever the circuit to solenoid coil 45 of control 29 is closed by switch 35. However, as'stated above, there is a time delay between the energizing of the relay 5'? and the opening of switch 51.

Operation-During normal operation of the steam boiler, bulb well 28, and encased thermal bulb 29, are totally or partially submerged in relatively quiet water in compartment '25 and the heat transferred by heat transfer rod 32 from the hot gases in chamber l4 to the bulb'well 28 is practically all consumed by the water sur- 4 rounding said bulb well so that the temperature of thermal bulb 29 remains substantially constant. However, when the water level in boiler it drops below the bottom level of bulb well 29, the water in compartment 25 drops to the same level and no longer contacts the bulb well. When this condition exists, the heat transferred by rod 92 is taken up by bulb well 28 and by thermal bulb 29. The expansible fluid in the thermal bulb expands rapidly causing bellows 3| to expand and close switch 35 to energize solenoid coil 45 of control 29 and open feed water valve 5|.

As feed water is supplied to the boiler the level therein rises to a point where bulb well 28 is again submerged in water in compartment 25. The heat transferred by rod 32 is now consumed by said water and the temperature of thermal bulb 29 drops, causing the fluid in said bulb, capillary tube 30 and bellows 3| to contract with the result that the bellows contracts and opens switch -3li,'which cleenergizes solenoid'coil45 and closes feed water valve 5|. 'During the above op- 'erations, depending upon the demands for steam from the boiler, fuel gas may have been continuously supplied to burner I.

Let us now assume that for some reason or other, feed water was not supplied to'the-boiler 'when valve 5| was opened, so that the water level in the boiler did not risesufliciently to contact and cool off bulb well 28 before the time allowed between the energizing of relay 51, that is the closing of switch 35, and the opening of switch5l had passed. Under these conditions, switch 51 is opened which deenergizes both the solenoid coil 45 of feed water control 20 and the solenoid coil 53 of fuel gas control l8, thereby causing both feed water valve 5| and gas supply valve 55 to close. In other words, the 'boileris shut down and remains in this condition until switch 51 is closed manually.

While I have illustrated and described but-one specific embodiment of my invention, it obviously may take other forms and it has other uses. Heat transfer rod 32, for example, may be replaced by any suitable means for continuously transmitting heat'to thermal bulb 29, which heat is consumed by'the water in the boiler so long as the water level'in the boiler is above a predetermined low.point and below which point the heat is transmitted to the thermal bulb. Sucha heating means might be an electric resistance element, a secondary heat transfer system'between the gas burner and the thermal bulb, or any such system that continuously supplies heat to the thermal bulb. Therefore, my invention is to be limited only by the following claims.

Iclaim:

1. In an atmospheric steam boiler, a casing forming a water space and a steam space, a plurality of fire tubes extending'through said casing, means for heating said-fire tubes, a combustion chamber located at one end of said fire tubes,.a water level control, said water level control comprisinga well the external surface of which is in open communication with'said water and steam spaces, a thermal element in said well, a heat transfer member extending from said thermal element into-said combustion chamber for'transf'erring heat from said combustion chamber to saidthermal'element, and operating mechanism associated with said thermal element for supplying water to said boiler upon a predetermined rise'in temperature of said thermal element.

2. In an atmospheric steam boiler, a casing forming a water space and a steam space, means for heating the water in said water space, a water level control, said water level control comprising a well the external surface of which is in open communication with said water and steam spaces, a thermal element in said well normally submerged in water from said water space, a heat transfer member having one end thereof arranged in intimate heat transfer relation with said thermal element and having its opposite end arranged to be heated by said heating means, and mechanism associated with said thermal element adapted to supply water to said boiler upon a predetermined rise in temperature of said thermal element.

3. In combination, a steam boiler, a heater for said boiler, a water level control device for said boiler comprising a thermal element normally submerged in water in said boiler, auxiliary means for heating said thermal element, said auxiliary -heating means including a solid metal member of good heat conducting material having one end thereof arranged in heat conducting relation with said thermal element and the opposite end thereof arranged to be heated by the boiler heater, said auxiliary heater being substantially ineffective to raise the temperature of said thermal element so long as said thermal element is submerged in water in said boiler, and mechanism associated with said thermal element to supply feed water to said boiler upon a predetermined rise in temperature of said thermal element by heat supplied thereto by said auxiliary heating means.

4. In an atmospheric steam boiler, a casing providing a Water space and a steam space, a valve for supplying feed water to said water space, a gas burner for heating said water, means for supplying gas to said burner, a control mechanism associated with said water and gas supply means, said control mechanism comprising a chamber in open communication with said water and steam spaces, a thermal element in said chamber, a heat transfer member associated with said thermal element and being adapted to transfer heat from said gas burner to said thermal element, operating mechanism associated with said thermal element for opening said water sup ply valve upon a predetermined rise in temperature in said thermal element, and delay mechanism incorporated in said operating mechanism for closing said gas supply means in a predetermined time after said water supply valve has been opened in the event that water is not supplied to said boiler.

5. In an atmospheric steam boiler, a casing providing a water space and a steam space, means for supplying feed water to said water space, a gas burner for heating the water in said space, means for supplying fuel gas to said burner, control mechanism for controlling said feed Water and gas supply means, said control mechanism comprising a well in open communication with said Water and steam spaces, a thermal element in said well normally submerged in water from said Water space, a heat transfer element for transferring heat from said gas burner to said thermal element, electrically operated mechanism associated with said thermal element for operating said water supply means upon a predetermined rise in temperature of said thermal element due to a lowering of the water level in said water space, and a delay mechanism incorporated in said electrically operated mechanism for operating said fuel gas supply means to shut 01f said gas supply in the event that said water supply means does not restore the water level in said water space within a predetermined period of time.

SVEN W. E. ANDERSSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,047,769 East et a1. Dec. 17, 1912 1,563,097 Milker Nov. 24, 1925 

